You might wonder if it is possible at all to generate psn codes. Psn codes are important for various purposes. Players of interactive games, especially those on the psn network know the importance of these games. You have to figure out methods of generating psn codes if at all it is possible. It all depends upon the website you refer to.
For example, see this psn code generator which is provided by one of the websites that specializes in it. It provides details on what psn codes are and how you can obtain them through various channels. It is indeed not possible to get whatever is available for a fee entirely for free. It would take quite a bit of an effort from your part to identify such a deal.
But some websites can indeed provide these codes. They will obviously be paying for them on your behalf. Naturally, they would expect something from you in return. This is the main reason why you will find most of these websites asking you to complete certain actions before they can provide you with their codes. Usually, they would require you to complete certain surveys to help them market specific products. These products can be their own or those of their partners.
Again, you will be leaving things upon chance after you complete these surveys. Completion of surveys is no guarantee that you will be getting psn codes for free. Likewise, avoiding surveys would definitely mean not being able to get your hands on any freely available rewards.